The invention relates to a process for the preparation of methane and/or ethane from a paraffin with 2-4 carbon atoms in the molecule or from a hydrocarbon mixture which consists of more than 75% w C.sub.2-4 paraffins and which C.sub.2-4 paraffins have an average molar carbon number which is at least 0.5 higher than that of the C.sub.2.sup.- paraffin fraction of the product, using a certain crystalline silicate as the catalyst.
In an investigation by the Applicant concerning the above-mentioned process it has been found that the methane+ethane weight percentage in the product is in the first place greatly dependent on the value of y in the formula which gives the overall composition of the silicate, and further on the pressure used in the process. It was found that to prepare a product whose methane+ethane weight percentage is acceptable for commercial use of the process, y should be at least 0.005 and the process should be carried out at a pressure above 10 bar.